System and method for deposition of a material on a substrate

ABSTRACT

A method and apparatus for improving coating of a substrate.

CLAIM OF PRIORITY

This application claims priority under 35 U.S.C. §119(e) to ProvisionalU.S. Patent Application Ser. No. 60/805,947 filed on Jun. 27, 2006,which is hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to a method and apparatus for depositing afilm on a substrate.

BACKGROUND

Material deposition on a substrate, such as glass, can be typicallyperformed on roller conveyed plates, continuous ribbons or on systemswith a conveyor that provide a solid backplane. Disturbances in thegeometry or air flow of such material deposition systems can result inchanges in film uniformity or film properties.

SUMMARY

A method of reducing edge effects in vapor deposition can includeintroducing a fixed substantially flat surface opposite a depositionnozzle in a vapor deposition system. A method of reducing edge effectsin vapor deposition can include introducing an exhaust basket opposite adeposition nozzle in a vapor deposition system, the exhaust baskethaving an intake surface extending beyond the width of a substrate whenpresent. These methods can be implemented by system includingsubstantially flat surface opposite the nozzle.

In one aspect, a system for depositing a material on a substrateincludes a deposition nozzle configured to introduce a vapor of amaterial toward a surface of a substrate, a transport mechanismconfigured to transport the substrate past the nozzle, and a firstsubstantially flat surface opposite the nozzle and in a void regionbetween elements of a transport mechanism. The system can include asecond substantially flat surface in a second void region betweenelements of a transport mechanism and adjacent to the firstsubstantially flat surface. Optionally, the system can include three ormore substantially flat surfaces in the void regions between elements ofthe transport mechanism. The system can include an exhaust basketopposite the nozzle.

In another aspect, a method for improving film uniformity on a substrateincluding placing a substantially flat surface opposite the nozzle andin a void region between elements of a transport mechanism, andintroducing a vapor through a nozzle toward the substantially flatsurface.

In another aspect, a vapor deposition system includes a vapor nozzlepositioned above a substrate, substantially flat surfaces opposite thenozzle, the substrate positioned above substantially flat surfaces,wherein the substantially flat surfaces are placed in between asubstrate transport mechanism, and an exhaust basket positioned beneaththe substantially flat surfaces. The exhaust basket can be connected toa source of reduced pressure.

A plane tangential to the transport mechanism can be offset between 0.1to 10 mm from the substantially flat surface. The substantially flatsurface can include graphite or boron nitride. The substantially flatsurface can be removable. The substantially flat surface can extendbeyond the width of the substrate when present. The substantially flatsurfaces can have adjustable positions. The substantially flat surfacescan extend beyond the nozzle to the region of the environmentalcontainment flows.

The exhaust basket can be connected to a source of reduced pressure. Theexhaust basket can be positioned beneath the substantially flat surface,can extend beyond the substantially flat surface in one dimension, andcan extend beyond the substantially flat surface in a second dimension.For example, the exhaust basket can have a length that is longer thanthe dimension of the substantially flat surface and a width that iswider than the substantially flat surface and the transport mechanism orsubstantially flat surface. The exhaust basket can include an adjustmentbar extending across the basket. The substantially flat surface can beadjustably attached to the bar. The exhaust basket can include aremovable base. A plurality of substantially flat surfaces can bepositioned in a plurality of corresponding void regions between elementsof the transport mechanism. The exhaust basket can be positioned overthe substantially flat surfaces. The method can include excess vapor inan exhaust basket.

The details of one or more embodiments are set forth in the accompanyingdrawings and the description below. Other features, objects, andadvantages will be apparent from the description and drawings, and fromthe claims.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a drawing depicting an embodiment of a vapor depositionsystem.

FIG. 2A is a drawing depicting an embodiment of the side view of anadjustment bar and the base of an exhaust basket.

FIG. 2B is a drawing depicting an embodiment of the front view of anadjustment bar and the base of an exhaust basket.

DETAILED DESCRIPTION

A vapor deposition method and system for depositing a film on asubstrate has been developed and found that can result in improvementsin variations in film properties and uniformity. Usual depositionmethods result in leading, trailing and side edge effects due to changesin vapor flow and exposure to a surface of a substrate. Such edgeeffects result in variation of the thickness of film deposits on theleading, trailing and side edges of a substrate. The method and systemcan be useful in reducing edge effects in vapor deposition and inreducing a ‘wrap around’ coating. The method of reducing edge effects invapor deposition can include introducing a fixed substantially flatsurface opposite a deposition nozzle in a vapor deposition system, orcan include transporting the substrate on substantially flat surfacesthat are positioned in between a substrate transport mechanism. Thesubstrate transport mechanism can be rollers. In another embodiment, amethod of reducing edge effects in vapor deposition can includeintroducing an exhaust basket opposite a deposition nozzle in a vapordeposition system. The exhaust basket can have an intake surfaceextending beyond the width of a substrate when present. The exhaustbasket can be connected to a source of reduced pressure to facilitatevapor deposition on a substrate. Using the systems and methods,thickness variations of the deposited layer at the edges of substratescan decrease to less than 25%, less than 20%, less than 15%, less than10%, less than 5%, less than 1%, less than 0.5% or less than 0.1% of theaverage layer thickness.

With reference to FIG. 1, a vapor deposition system 100 includes anozzle 10, a substantially flat surface 20, transport mechanism 30, asubstrate 40, and an exhaust basket 50 connected to a source of reducedpressure 60. The vapor deposition system 100 includes a nozzle 10 thatcan be configured to introduce a vapor of a material onto a surface of asubstrate 40 to coat the surface with the material. The vapor can beintroduced at atmospheric pressure, at a pressure above atmosphericpressure or at a pressure below atmospheric pressure. Nozzle 10 can bepositioned above a substrate 40. Substrate 40 can be a glass sheet.Substrate 40 can be heated during the processing to a substratetemperature. Substrate 40 can be transported by any appropriatetransport mechanism to the vapor deposition system 100, such as rollers,or a conveyor belt, driven, for example, by an attached electric motor.Substantially flat surface 20 can be supported by bar 62 and positionedwith an adjustable connector 65. Depending on the configuration of thesystem, a second substantially flat surface 21 can be placed in othervoid regions between elements of transport mechanism 30. Substantiallyflat surface 21 can be supported by bar 62 and positioned with anadditional adjustable connector 66.

The method and system can be used to form a coating by vapor deposition,including dielectric coatings, metal coatings, and semiconductorcoatings using the systems and methods described herein. Also, dopantscan be included to enhance the deposition and properties of theresulting coatings or films, as appropriate. For example, the method andsystem can be used to deposit coatings of tin oxide or silicon dioxideon a surface of a glass substrate. The vapor can be introduced atatmospheric pressure, at a pressure above atmospheric pressure, or at apressure below atmospheric pressure. In certain circumstances, thesystem can include a curtain of inert gas, such as nitrogen, that cancontain and isolate the vapor to a deposition region.

The substantially flat surface can be positioned opposite the depositionnozzle. The substantially flat surface can be positioned in between asubstrate transport mechanism. The substrate transport mechanism can bea roller. The substantially flat surface is used to create an air flowthat is minimally disturbed when a substrate is not present. Thisreduces the leading and trailing edge effect on the substrate andprovides less variation in film uniformity and film properties and alsoreduces wrap around or back surface coating. For example, thesubstantially flat surface or surfaces can be positioned in between atleast two rollers. The plane tangential to the two rollers can be offsetbetween 0.1 to 10 mm from the substantially flat surface. Thesubstantially flat surfaces can be positioned in between an appropriatenumber of rollers depending on the desired length of the flat surfacearea to be presented to the nozzle or nozzle array. Alternatively, therecan be multiple substantially flat surfaces in between multiple rollers.For example, there can one substantially flat surface in between atleast two rollers, two substantially flat surfaces in between threerollers. The number of deposition nozzles can be equal to the number ofsubstantially flat surfaces or there may be multiple substantially flatsurfaces for each nozzle. The positioning of the substantially flatsurfaces can reduce or prevent turbulence on the edges of the substrate40 and allows for an even deposition of vapor on the edges of thesubstrate. The positioning of the substantially flat surface candecrease flow disturbance or allow minimal flow disturbance that can becreated by lack of substrate as the backplane provides similar geometryduring the entire process. Crossweb edges are also less impacted becausethe substantially flat surfaces provide a virtual substrate to coat inbetween the edge of one substrate and the edge of another substratethereby reducing or eliminating leading and trailing edge effects aswell as side edge effects. Wrap around coating of the opposite side ofthe substrate is also reduced.

The substrate 40 can be positioned above substantially flat surface 20.The substantially flat surfaces 20 can extend beyond the width ofsubstrate 40 when present. For example, the width of the substantiallyflat surface can be more than 0.1%, more than 1%, more than 5%, morethan 10%, more than 25%, more than 40%, or more than 50% greater thanthe width of the substrate. The substantially flat surface can also belonger than the length of the substrate. For example, the length of thesubstantially flat surface can be more than 0.1%, more than 1%, morethan 5%, more than 10%, more than 25%, more than 40%, or more than 50%greater than the length of the substrate. The substantially flatsurfaces 20 can be removable. The substantially flat surfaces can becleaned without disassembling the entire system. The substantially flatsurfaces 20 can include graphite or boron nitride or any other materialsthat are stable under deposition conditions. The substantially flatsurfaces 20 and/or exhaust basket 50 can be configured to modify apre-existing vapor deposition system.

Referring to FIG. 1, the vapor deposition system 100 can include anexhaust basket 50 opposite the nozzle 10. The exhaust basket can be usedto collect the excess vapor or carrier gas from the system. The exhaustbasket 50 can be positioned beneath the substantially flat surfaces 20.The exhaust basket 50 can be connected to a source of reduced pressure60. The source of reduced pressure can be a vacuum pump or fan systemdesigned to draw unreacted vapor and/or reaction products out of thedeposition region of the system.

Referring to FIG. 2A, the exhaust basket 50 can extend beyond thesubstantially flat surface 20 in one dimension. In certaincircumstances, the exhaust basket 50 can also extend beyond thesubstantially flat surface 20 in a second dimension. For example, theexhaust basket can have an intake plane positioned beneath thesubstantially flat surface. Alternatively, the exhaust basket can havean intake plane positioned such that it is even with the substrate planeor positioned above the substrate plane.

The exhaust basket 50 can have a length that is longer than thedimension of the substantially flat surface 20. For example, the lengthof the exhaust basket can be more than 0.1%, more than 1%, more than 5%,more than 10%, more than 25%, more than 40%, or more than 50% greaterthan the corresponding length of the substantially flat surface. Theexhaust basket 50 can have a width that is wider than the substantiallyflat surface 20 and rollers 30. For example, the width of the exhaustbasket can be more than 0.1%, more than 1%, more than 5%, more than 10%,more than 25%, more than 40%, or more than 50% greater than the width ofthe substantially flat surface. The exhaust basket dimensions andpositions are configured so that there are decreased or minimal flowchanges in the vapor stream as the substrate is transported into and outof the vapor stream. This helps provide an even deposition of vapor onthe edges of the substrate thereby providing improved film uniformityand quality on the surface of the substrate.

Referring to FIG. 2B, the exhaust basket 50 can include a supportbracket 70 extending across the basket, the substantially flat surface20 being adjustably attached to the support bracket 70. The exhaustbasket can also include a removable base 80. The removable base 80 canbe attached to, hinged or otherwise places on the support bracket 70.Referring to FIG. 2B, the removable base 80 can be hinged onto a lip 90on the support bracket 70. The removable base 80 can be positioned sothat it is easily accessed and cleaned. The exhaust basket 50 has adimension greater than the substantially flat surface 20. The exhaustbasket can include a lip that brings the edges up to the same plane asthe surfaces of the substantially flat plate, or above the plane. Thebasket shape can be modified, for example, edge height, gap from edge offlat plates, or gap from transport mechanism, etc., to improve thequality of the coated substrate.

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention.Accordingly, other embodiments are within the scope of the followingclaims.

What is claimed is:
 1. A system for depositing a material on asubstrate, comprising: a deposition nozzle configured to deposit a firstportion of a vapor of a material as a film on a first surface of thesubstrate; a transport mechanism configured to transport the substratepast the nozzle; a first substantially flat surface opposite the nozzleand in a void region between elements of a transport mechanism; a secondsubstantially flat surface in a second void region between elements of atransport mechanism and adjacent to the first substantial flat surface;wherein the first and the second substantially flat surfaces arepositioned with its own individual adjustable connector; and an exhaustbasket positioned substantially directly beneath the first substantiallyflat surface, wherein the exhaust basket is connected to a source ofreduced pressure, the exhaust basket having an intake, the intakepositioned beneath the nozzle and opposite a second surface of thesubstrate and above the source of reduced pressure, and extending beyondthe width of the substrate and configured to receive a second portion ofthe vapor from the deposition nozzle which is not deposited on the firstsurface of the substrate.
 2. The system of claim 1, wherein a planetangential to the transport mechanism is offset between 0.1 to 10 mmfrom the substantially flat surface.
 3. The system of claim 1, whereinthe substantially flat surface includes graphite or boron nitride. 4.The system of claim 1, wherein the substantially flat surface isremovable.
 5. The system of claim 4, wherein the exhaust basket extendsbeyond the substantially flat surface in one dimension.
 6. The system ofclaim 5, wherein the exhaust basket extends beyond the substantiallyflat surface in a second dimension.
 7. The system of claim 4, whereinthe exhaust basket includes a removable base.
 8. The system of claim 1,wherein the substantially flat surface extends beyond the width of thesubstrate when present.
 9. The system of claim 8, wherein the exhaustbasket comprises an bar extending across the basket, the adjustableconnector being attached to the bar.
 10. The system of claim 1, furthercomprising a plurality of substantially flat surfaces positioned in aplurality of corresponding void regions between elements of thetransport mechanism.
 11. A vapor deposition system comprising: a vapornozzle positioned above a substrate and configured to deposit at least aportion of a vapor material as a film on a first surface of thesubstrate; substantially flat surfaces opposite the nozzle, thesubstrate positioned above the substantially flat surfaces, wherein thesubstantially flat surfaces are placed in between portions of asubstrate transport mechanism and wherein each substantially flatsurface is positioned with its own individual adjustable connector; andan exhaust basket positioned substantially directly beneath the firstsubstantially flat surface, wherein the exhaust basket is connected to asource of reduced pressure, the exhaust basket having an intake, theintake positioned beneath the nozzle and opposite a second surface ofthe substrate and above the source of reduced pressure, and extendingbeyond the width of the substrate and configured to receive the vapornot deposited on the first surface of the substrate by the vapor nozzle.12. The vapor deposition system of claim 11, wherein a plane tangentialto the substrate transport mechanism is offset between 0.1 and 10 mmfrom the substantially flat surfaces.
 13. The vapor deposition system ofclaim 11, wherein the substantially flat surfaces are removable.
 14. Thevapor deposition system of claim 11, wherein the exhaust basket has alength that is longer than the dimension of the substantially flatsurface.
 15. The vapor deposition system of claim 11, wherein theexhaust basket has a width that is wider than the substantially flatsurface and the transport mechanism.
 16. The vapor deposition system ofclaim 11, wherein the exhaust basket is removable.